IT IS sometimes said that corruption is the purpose of Indian politics. Increasingly, it can be said with confidence, graft is the subject of politics. We recently ran an interview with India’s unlikely graft-buster, the Comptroller and Auditor-General (CAG), whose investigations are as explosive as his title is turgid.

He has just published a new report on the murky doling out of coal fields, which has been worth billions of dollars to big firms. In political terms this is a stick of dynamite. Uproar ensued as soon as it landed on parliament’s doorstep on August 21st. Both chambers were shut within minutes. Parliament was shouted down again the next day, in a series of riotous scenes. The opposition chanted slogans denouncing the contracts and declaring that “all of Congress is black” from its dirty dealing (सारी कांग्रेस काली है). It wants the head of Manmohan Singh, the prime minister, and claims it will bawl parliament to a standstill every day until he resigns.

Until now little dirt has stuck to Mr Singh, despite the scandals under his government’s watch, including the crooked award of mobile-phone licences in 2008, which was also investigated by the CAG and led to a minister facing trial. Mr Singh has, and perhaps cultivates, a reputation for being a cuddly, grandfatherly type, around whom venal colleagues occasionally run rings. But this time it may be hard for him to deny responsibility. For much of the period in question he was directly in charge of the ministry of coal, as well as being prime minister.

At a minimum the report makes clear that lousy decisions were made. India’s state-owned coal-mining monopolist cannot dig up enough coal to supply the country’s needs. The government rightly decided to get more coal fields into the hands of private firms. It promoted a policy to establish privately owned “captive” mines. Each would supply a particular private project—an electricity or steel plant.

But how to get those coal fields from public hands into private? As far back as 2004 the government discussed auctions. After all, if coal fields were just doled out for free by the state, the recipients would enjoy “windfall profits”, it acknowledged. Yet that is exactly what then happened. Some 57 fields were given to private firms up until 2009 (most of them in a flurry, between 2004-2006). A government screening committee played god. There is a case for natural resources to be allocated rather than auctioned, but only if this is done transparently. Sadly the committees’ records and minutes do not explain how it decided who got lucky, according to the CAG’s report.

These were big decisions. The total value of the coal fields that were, in effect, given to the private sector is put at $34 billion by the CAG. That calculation is hotly disputed. Whatever the fine print, the sum in question is likely to be at least $10 billion. Many of India’s big industrial clans and conglomerates benefited, including the Jindals, Aditya Birla, Tata Sons, Essar Group and Adani.

The government, if it manages to get a word in, will argue it was following a tradition of administrative fiat and was in a hurry to boost coal production. But there is a kink in this argument. The actual output from those captive mines turned out to be disappointing—almost as if some owners had never planned to dig very hard in the first place. The government made little effort to monitor their output.

And there was already a pong in the air. India is facing a new era of “resource cronyism”, say some prominent economists, including one who has just been appointed as the government’s chief economics adviser. Financial types in Mumbai have long said some of the coal allocations were iffy. The parallels with the 2G mobile-phones scandal, where spectrum was handed by fiat out almost for free, are uncanny. Police investigators, or perhaps the supreme court, may decide to try establishing how each mine was allocated. At least until they have, allegations of favouritism, and graft, will sting.

The opposition, led by the Bharatiya Janata Party (BJP), is being hypocritical as well as hysterical. As the government has pointed out, several bigwigs in the BJP supported the policy of allocating coal fields by committee, in preference to auction. Still, the damage to the ruling Congress-led coalition is likely to be real. It had known about the report for months. Even so there must be an outside chance that Mr Singh, who is 79, decides he has had enough. Supposing he stays, the air in parliament is likely to be fouler than ever, minimising the chance of any cross-party co-operation. Hopes that this legislative session might see a flurry of much-needed economic reforms, have for now been cast into a deep black pit.